Facsimile machines and other data-handling customer premise equipment are introduced not only into offices but individual homes in great numbers. As personal computers are found in more homes, users of computer networks such as "Internet" by way of telephone networks through modems are increasing in phenomenal numbers. The majority of these data transactions through modems or fax machines use existing local exchange carrier networks for data transmission. Fax machines, computers, and telephone sets at a customer premise are connected by local access to a central telephone switching office. The local access is variously called as subscriber's loop, local loop, drop etc. In cases of CATV or wireless, local access is also called subscriber connection, wireless access etc. It has been shown that the majority access "Internet" by dial-up telephone connection. FIG. 1 shows how a telephone, fax computer and other intelligent agents are typically connected through a publicly switched telephone network and data networks and their interconnections. Terminal equipment at a customer premise consist of a telephone set, fax machine, a personal computer etc., and are collectively called CPE which stands for customer premise equipment. CPE 10 is connected through inside wiring 12 at the customer premise and then through the feeder/distribution plant (also called subscriber's loop, local access loop) 14 to an access module (e.g. linecard) 16. The linecard is in turn connected to a local switch 18 that is part of the public switched telephone network (PSTN) 20. PSTN operates in channelized mode and provides continuous connection to another subscriber 22. The telephone service is established through a connection protocol (e.g. dialup, on-hook/off-hook protocol) and upon connection provides fixed channelized bandwidth on a continuous basis for the duration of the call. A facsimile connection is essentially the same as a telephone connection with the exception of the presence of a modem 24 at each facsimile terminal. The figure also shows a connection involving a data network. For such a connection, the CPE (e.g. computer) also requires a telephone subscriber's loop to the PSTN by dialup service which connects to a data service provider 26 through its own subscriber's loop 28. The data service provider 26 then provides a data connection through a data network 30 to a database service or other data service subscribers.
The present CATV service is mainly unidirectional, broadcast from a service provider through its own network which has no connection to any other network. In small scale, experimental multimedia telecommunications networks are being field tested at some locations. Referring to FIG. 2, such CATV access to telecommunications services is illustrated. In the figure, the CPE (e.g. TV) is connected through local wiring (possibly coax or fiber optic) to a converter 40, sometimes called a set-top box, that connects to the drop cable, taps, and splitters to a CATV access module 42 through an access loop 44 (most likely fiber optic or coax) and then through to the CATV services provider (cableco) 46 or other service providers 48 at which point connections to other service networks 50 can be provided. It is common for each subscriber to require a separate bidirectional channel for two-way telecommunications services. FIG. 2 also shows a wireless connection. For wireless service, the CPE is connected through the wireless interface or CPE connector 40 and a radio frequency channel 52 to a base station or access module 42, and then to the wireless service provider who in turn provides a connection to the specific service or transport network such as PSTN 54. During the entire call, a fixed amount of channel bandwidth is allocated to the service even though the specific radio frequency channel may change in a seemingly uninterrupted manner during the call.
In all these cases, the CPE is provided with channelized access of a fixed bandwidth, which makes it difficult to provide other services or to change service parameters during the time that the connection is established.
Computer connections are generally much longer in duration than voice or other connections. Computers perform data transactions in packets and their traffic is very bursty. The bursty traffic is more suitable for statistical multiplexing and is most efficiently handled by specially designed data networks such as packet switched networks. At present, however, all publicly switched traffic, data and voice, is sent over the subscriber's loop and interoffice trunking in a circuit switched network connection to destination customer premise equipment or to a data network.
Multimedia broadband switched networks by the name of the "Information Superhighway" have been widely proposed. This superhighway may carry different types of traffic seamlessly, accepting voice, data and video information from any terminal and delivering it to any other terminals simultaneously. At present, however, different types of networks, both channelized and packetized, exist separately and independently.
In circuit switched networks, a connection is maintained during the whole duration of a call through switches and other associated network elements, regardless of the type of call. Only one circuit switched connection can be maintained for the call. No broadcast or multicast through the circuit switched network is possible. Today, telephone networks are becoming increasingly more occupied by data traffic which generates no additional revenues to the local exchange carriers. Furthermore, access to worldwide computer networks, such as "Internet" etc. is now being provided by commercial network service providers, such as "America Online", "SprintLink" etc. Using PSTN as the access, the network service providers provide access to various other private networks, academic networks etc., which contain vast numbers of databases for value added services.
FIG. 3 shows diagrammatically how data networks such as "Internet" are accessed through a telephone subscriber's loop. An individual end user subscribes to the service of a commercial network service provider 60. Access to a data network is usually by dialing the telephone number of a commercial data network service provider using a modem. Thus the end user CPE 62 uses a modem and makes a dialup connection to a local switch 64 by a subscriber's loop 66. The local switch 64 makes an inter-office trunk connection 68 to a terminating local switch 70 within a PSTN 72. The terminating local switch connects through a local loop 74 and a terminating modem to a service provider 60. After a proper modem handshaking protocol, the user inputs the address of a destination such as the "Internet" server with whom he desires a connection. Data networks and database services are accessed using a TCP/IP protocol. The "Internet" packet is routed over a T-1 link 76 (or other facilities) to the Internet 78. In this arrangement, the local switches 64 and 70 as well as the interoffice trunk 68 are occupied for the duration of the connection, which is usually measured in hours rather than the shorter holding time associated with voice calls which are measured in minutes. Consequently, very expensive common equipment in the PSTN is required for the duration of the "Internet" access, even during a period of inactivity by the end user.
The use of a telephone network by network service users increases usage of the telephone network enormously without a proportionate increase of additional revenues to the telephone company. It is also cumbersome for an individual user to access various networks. It will be shown below that the present invention reduces this investment in the PSTN (31) as well as enhances the capabilities of the overall global communications network.
There have been many patents which address network data transfer issues. For example, U.S. Pat. No. 4,178,480, issued Dec. 11, 1979 (Carbrey), describes a single multiplexing circuit which permits use between a central communication system and a remote communication circuit for concurrently transmitting outgoing voice signals, outgoing data, and outgoing auxiliary signals from the remote communication circuit to the central communication system via a single pair of wires. Voice signals are audio signals in the voice frequency band. Input and output data streams comprise periodic bursts of bipolar pulses in PAM format transmitted in the voice band and the auxiliary signals are bipolar pulses in PWM format transmitted also in the voice band but during a silent period of data signals.
U.S. Pat. No. 4,608,686, issued Aug. 26, 1986 (Barselloti), describes a circuit for transmitting both voice and data at the same time between a subscriber's set and a switching exchange via a bidirectional wire link.
U.S. Pat. No. 5,410,754, issued Apr. 25, 1995 (Klotzbach et al), teaches an interface between a wire-line carrier system and a remote host on a LAN. The interface includes a protocol conversion between PCM data and TCP/IP packet data.
U.S. Pat. No. 5,267,301, issued Nov. 30, 1993 (Nishii), is directed to an interfacing device for discriminate voice and fax signals.
U.S. Pat. No. 4,903,263, issued Feb. 20, 1990 (Patel), relates to an adjunct device to existing switches for providing ISDN capabilities.
Hereinafter, the following terms will be used in connection with the description of the invention.
Network access (local access network)--A managed facility between the CPE and communications networks (e.g. copper pairs, coaxial, fiber, wireless). PA1 Channelized protocol--Communications protocol requiring end-to-end allocation of network resources of a specified bandwidth for the duration of the session, independent of the actual information transfer activity (e.g. a circuit switched network, such as PSTN, implements a channelized protocol for telephone traffic). PA1 Non-channelized protocol--Communications protocol allocating network resources for the duration of actual information transfer activity (e.g. a packet switched network implements a non-channelized protocol for transfer of signals). PA1 Traffic in channelized format--Communications traffic using a channelized protocol. PA1 Traffic in non-channelized format--Communications traffic using a non-channelized protocol.